Olsalazine is contraindicated during pelvic radiation therapy: Results of a double-blind, randomized clinical trial

James A. Martenson, Glenn Hyland, Charles G. Moertel, James A. Mailliard, Judith R. O'Fallon, Roger T. Collins, Roscoe F. Morton, Hamed H. Tewfik, Randy L. Moore, Albert R. Frank, Rodolfo E. Urias, Richard L. Deming

Research output: Contribution to journalArticlepeer-review

61 Scopus citations


Purpose: A randomized clinical trial from Great Britain suggested a possible beneficial effect of acetylsalicylate in the prevention of radiation-induced bowel toxicity. Olsalazine is an orally administered drug designed to deliver 5-aminosalicylate to the large bowel with minimal systemic absorption. A randomized clinical trial was undertaken to assess the effectiveness of olsalazine in preventing acute diarrhea in patients receiving pelvic radiation therapy. Methods and Materials: Patients receiving pelvic radiation therapy were randomized, in double-blind fashion, to olsalazine 250 mg, two capsules twice daily, or an identical appearing placebo, two capsules twice daily. Patients were then evaluated weekly during radiation therapy for the primary study endpoint, diarrhea, as well as rectal bleeding, abdominal cramping, and tenesmus. Results: The study was closed early, after entry of 58 evaluable patients, when a preliminary analysis showed excessive diarrhea in patients randomized to olsalazine. The incidence and severity of diarrhea were worse in patients randomized to olsalazine (p = 0.0036). Sixty percent of the patients randomized to olsalazine experienced Grade 3 or 4 diarrhea compared to only 14% randomized to placebo. There was also a trend toward higher incidence and greater severity of abdominal cramping in patients who were randomized to olsalazine (p = 0.084). Conclusion: Administration of olsalazine during pelvic radiation therapy resulted in an increased incidence and severity of diarrhea. Olsalazine is contraindicated in patients receiving pelvic radiation therapy.

Original languageEnglish (US)
Pages (from-to)299-303
Number of pages5
JournalInternational Journal of Radiation Oncology Biology Physics
Issue number2
StatePublished - May 1 1996


  • Adverse effects
  • Olsalazine
  • Pelvic radiation therapy

ASJC Scopus subject areas

  • Radiation
  • Oncology
  • Radiology Nuclear Medicine and imaging
  • Cancer Research


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